"Thought Leaders" meaning popularizers? In that case I suggest all of BreadTube, Peter Coffin in particular, as well as Jacobin Magazine, whose editor Bhaskar Sunkara just published a book (The Socialist Manifesto) that is pretty great.

"Thought Leaders" meaning philsophers? Noam Chomsky is one of the more famous ones. Mark Fisher has put out some pretty good philosophy as well. Slavoj Zizek might come up as an example here as well, but I'm not entirely sure I can recommend his work.